1. Field of Invention
The present invention relates generally to optical fiber, and more particularly to optical fiber used to transmit light for medical treatments.
2. Background of Art
Photodynamic therapy (PDT) is a treatment that uses a drug, called a photosensitizer or photosensitizing agent, and a particular type of light. When photosensitizers are exposed to a specific wavelength of light, they produce a form of oxygen that kills nearby cells.
Each photosensitizer is activated by light of a specific wavelength. This wavelength determines how far the light can travel into the body. Thus, doctors use specific photosensitizers and wavelengths of light to treat different areas of the body with PDT.
In the first step of PDT for cancer treatment, a photosensitizing agent is injected into the bloodstream. The agent is absorbed by cells all over the body but stays in cancer cells longer than it does in normal cells. Approximately 24 to 72 hours after injection, when most of the agent has left normal cells but remains in cancer cells, the tumor is exposed to light. The photosensitizer in the tumor absorbs the light and produces an active form of oxygen that destroys nearby cancer cells.
In addition to directly killing cancer cells, PDT appears to shrink or destroy tumors in two other ways. The photosensitizer can damage blood vessels in the tumor, thereby preventing the cancer from receiving necessary nutrients. PDT also may activate the immune system to attack the tumor cells.
The light used for PDT can come from a laser or other sources. Laser light can be directed through fiber optic cables (thin fibers that transmit light) to deliver light to areas inside the body. For example, a fiber optic cable can be inserted through an endoscope (a thin, lighted tube used to look at tissues inside the body) into the lungs or esophagus to treat cancer in these organs. Other light sources include light-emitting diodes (LEDs), which may be used for surface tumors, such as skin cancer.
PDT is usually performed as an outpatient procedure. PDT may also be repeated and may be used with other therapies, such as surgery, radiation, or chemotherapy.
Commonly in use in PDT are plastic cylindrical diffusers used to illuminate the cancer cells. With specific reference to FIG. 1, these cylindrical diffusers 10 are available only in fixed lengths L and illuminate uniformly throughout the entire length of the diffuser; light is not diffused from the area of the diffuser outside dotted box 12. Because tissue to be illuminated in medical procedures, such as, for example, cancerous tumors, are generally not regular or uniform, there is a need to specifically alter the illumination pattern of a cylindrical diffuser. Additionally, regardless of preoperative planning techniques, there is not a method for adjusting the amount of illumination in situ without replacing the diffuser.
Corning Incorporated offers a technology sold under the brand name FIBRANCE® light diffusing fiber in the medical space. U.S. Patents directed to this diffusing fiber include U.S. Pat. No. 8,591,087 and U.S. Pat. No. 8,926,143, the disclosures of which are hereby incorporated by reference in their entirety herein.
As stated, current technology requires discrete length diffusion fibers to be used; if a different sized diffuser is needed a new device must be opened and inserted into the patient. Such a process wastes time and increases expense associated with the procedure.
3. Illustrative Objects and Advantages
It is therefore an object and advantage of the present invention to provide a use for a single diffusing fiber and an opaque sheath or patterned sheath to control exposure of the fiber to the surrounding tissue.
It is another object and advantage of the present invention to provide use of a diffusing fiber that decreases costs associated with certain medical procedures, decreases time associated with certain medical procedures, and decreases damage to surrounding healthy tissue during certain medical procedures.
Other objects and advantages of the present invention will in part be obvious and in part appear hereinafter.